The image you've uploaded contains a series of calculations related to vapor pressure, relative humidity, and specific humidity. Here's a breakdown of the steps and concepts covered in the image:

1. Saturation Vapor Pressure (SVP): The formula provided is: $SVP(hPa) = 6.11 \times 10^{(7.5 \times T_{dp}) / (T_{dp} + 237.3)}$ Where $T_{dp}$ is the dew point temperature in Celsius. For $T_{dp} = 28.8^\circ C$, this yields: $SVP \approx 6.11 \times 10^{(7.5 \times 28.8) / (28.8 + 237.3)} \approx 6.11 \times 6.525 \approx 39.85 \, hPa$ This is the saturation vapor pressure at that dew point.

2. Actual Vapor Pressure (AVP): The formula for calculating the actual vapor pressure at the given relative humidity (RH) is: $AVP = SVP \times \frac{RH}{100}$ Substituting in the saturation vapor pressure (SVP = 39.85 hPa) and relative humidity $RH = 90\%$: $AVP \approx 39.85 \times \frac{90}{100} \approx 35.865 \, hPa$ This is the actual vapor pressure under the current conditions.

3. Specific Humidity (SH): To calculate specific humidity, the formula used is: $SH = \frac{0.622 \times AVP}{P - AVP}$ Where $P$ is the atmospheric pressure, which is approximately $1013 \, hPa$ at sea level. Using the actual vapor pressure $AVP = 35.865 \, hPa$: $SH = \frac{0.622 \times 35.865}{1013 - 35.865} \approx \frac{22.307}{977.135} \approx 0.0228$ This gives a specific humidity of 0.0228.

4. Conversion to g/kg: Finally, specific humidity is converted from a dimensionless value to grams per kilogram by multiplying by 1000: $SH \approx 0.0228 \times 1000 \approx 22.8 \, g/kg$ This is the final answer: the specific humidity of the air parcel is approximately 22.8 g/kg.

Would you like more details on any of these steps or need further clarification?

Here are five related questions to expand on this:

1. How does the dew point temperature affect the saturation vapor pressure?
2. What is the significance of relative humidity in determining actual vapor pressure?
3. How would changes in atmospheric pressure affect the specific humidity calculation?
4. Can you explain the physical meaning of specific humidity in weather systems?
5. How does temperature variation influence specific humidity?

Tip:

When solving humidity problems, remember that higher temperatures generally increase the air's capacity to hold moisture, thus increasing the saturation vapor pressure.